Although this solution kept the noise out of the speakers, and didn’t seem to effect cell signal, it did have an impact on bluetooth reception. I was getting lots of static when the iPhone was more than about 12″ from my bluetooth headset (both Plantronics and Jawbone). Needless to say, using bluetooth on a daily basis became a hassle.

I have found a new and improved technique that will keep bluetooth static to a minimum and the noise out of your speakers; instead of aluminum foil, use the foil-paper that you find in a pack of cigarettes. For whatever reason, it seems to block the exact right amount of GSM and keep bluetooth interference to a minimum. In fact, it may even block the speaker interference better – I haven’t heard a peep since the foil-paper.

Take the foil out from a fresh pack of smokes (Fig. A),
or find an empty box and remove the inner lining (Fig. B):

Fig. A:

Fig. B:

Here’s what you’ll get:

The size of the foil-paper is almost perfect, but you’ll probably want to cut/tear a bit off the sides so it fits better. Using the old aluminum foil method, affix the single piece of foil-paper to the area indicated below:

This is especially nice if you have an iPhone case (like an Otterbox), so you don’t actually need to tape the foil to your phone. Here’s the foil-paper tucked into the front cover of the Otterbox (back cover off) — this size/placement works perfectly for me:

No more speaker interference and no more (or at least much less) bluetooth interference!